Plasma processing apparatus

ABSTRACT

In a plasma processing apparatus for processing a substrate by plasmatizing a process gas introduced into a processing container, an introducing unit which introduces the process gas is formed on a ceiling surface of the processing container; a gas retention portion which gathers the process gas supplied from the outside of the processing container through a supply passage, and a plurality of gas ejection holes which allow communication between the gas retention portion and the inside of the processing container are formed in the introducing unit; a gas ejection hole is not formed in a location of the gas retention portion that faces an opening of the supply passage; and a cross section of each of the gas ejection holes has a flat shape.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application claims the benefit of Japanese Patent Application No.2009-202634, filed on Sep. 2, 2009, in the Japan Patent Office, thedisclosure of which is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plasma processing apparatus used insemiconductor manufacturing.

2. Description of the Related Art

Plasma processing apparatuses that generate plasma by propagatingmicrowaves from slots formed in a Radial Line Slot Plate (Radial LineSlot Antenna: RLSA) into a processing container are conventionally usedin the manufacturing field of semiconductor devices (for example, referto Patent Document 1). These RLSA-type plasma processing apparatuses arecapable of forming uniform plasma having high density and a low electrontemperature, and performing plasma-process of large-sized semiconductorwafers uniformly and fast. A well-known example of the plasma process isa process of etching a surface of a substrate by using a CF-based gas ora CFH-based gas.

In the plasma processing apparatuses, the microwaves are propagated intothe processing container through a dielectric material disposed on aceiling surface of the processing container. Then, a process gasintroduced to the processing container is plasmatized by energy of themicrowaves, and thus etching is performed on the surface of thesubstrate. Generally, an introducing unit for introducing the processgas to the processing container is disposed, for example, on a sidesurface of the processing container. Also recently, in addition to theintroducing unit disposed on the side surface of the processingcontainer, an introducing unit for introducing the process gas is formedon the ceiling surface of the processing container. Accordingly,improvement in the uniformity of etching on the surface of the substrate(Radical Distribution Control (RDC)) is obtained by optimizing a ratioof an amount of a process gas introduced from the introducing unit onthe side surface to an amount of a process gas introduced from theintroducing unit on the ceiling surface.

(Patent Document 1) Japanese Laid-Open Patent Publication No. 2009-99807

However, in a conventional plasma processing apparatus, a carbon-basedproduct may be generated and adhered to an introducing unit forintroducing a process gas to a processing container. Also, the processgas may be unable to be smoothly introduced to the processing containeras a gas ejection hole formed in the introducing unit is blocked by theadhered product. When the gas ejection hole is blocked by the adheredproduct, a balance between the amounts of process gases introduced froman introducing unit on a side surface and an introducing unit on aceiling surface may change, and thus etching uniformity over a surfaceof a substrate may deteriorate. Moreover, an operation of solving ablocking of the gas ejection hole is troublesome, and thusmaintenanceability is deteriorated.

SUMMARY OF THE INVENTION

To solve the above and/or other problems, the present invention providessuppression of generation and adhesion of a carbon-based product in anintroducing unit for introducing a process gas to a processingcontainer.

According to an aspect of the present invention, there is provided aplasma processing apparatus which processes a substrate by plasmatizinga process gas introduced into a processing container, wherein anintroducing unit which introduces the process gas is formed on a ceilingsurface of the processing container; a gas retention portion in whichthe process gas supplied from the outside of the processing containervia a supply passage stays tentatively before being distributed, and aplurality of gas ejection holes which allow communication between thegas retention portion and the inside of the processing container areformed in the introducing unit; a gas ejection hole is not formed in alocation of the gas retention portion that faces an opening of thesupply passage; and a cross section of each of the gas ejection holeshas a flat shape.

In the gas retention portion, a recess portion accommodating the processgas supplied from the supply passage to the gas retention portion may beformed in the location of the gas retention portion that faces theopening of the supply passage. In this case, the opening of the supplypassage may be located, for example, in the center of the gas retentionportion, and the plurality of gas ejection holes may be disposed in acircumferential direction having the opening of the supply passage in acenter. Also, each of the gas ejection holes may have a flatcross-sectional shape that is long in the circumferential directionhaving the opening of the supply passage in a center and short in aradial direction having the opening of the supply passage in a center.Also, the gas ejection holes may be formed in an injector block formedof, for example, a conductive material, and the injector block may beelectrically grounded. In this case, a protective film which increasesremovability for adhered product may be formed on a surface of theinjector block that faces the inside of the processing container. Also,a periphery of the opening of the gas ejection hole that faces theinside of the processing container may have a tapered shape. Also, adielectric window, which is disposed on a ceiling portion of thecontainer as a ceiling member, is shaped tapered inwardly so that thegas ejection holes are not directly seen by being shaded by thedielectric window when viewed upward from the inside of the processingcontainer.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent by describing in detail exemplary embodimentsthereof with reference to the attached drawings in which:

FIG. 1 is a longitudinal-sectional view showing a schematicconfiguration of a plasma processing apparatus according to anembodiment of the present invention;

FIG. 2 is a cross-sectional view taken along line X-X of FIG. 1, andshows a state of a lower surface of a dielectric window;

FIG. 3 is a magnified sectional view of an introducing unit forintroducing a process gas, which is formed on a ceiling surface of aprocessing container;

FIG. 4 is a plan view of an injector member attached to an introducingunit for introducing a process gas;

FIG. 5 is a cross-sectional view of an injector member taken along lineY-Y of FIG. 4;

FIG. 6 is a magnified view of a gas ejection hole;

FIG. 7 is a magnified cross-sectional view of a conventional introducingunit for introducing a process gas;

FIG. 8 is a view for explaining injector blocks of Comparative Examples1 through 5 and Embodiments 1 and 2;

FIG. 9 is a graph showing a relationship between pressures in splittersof Comparative Example 1 and Embodiment 1, and a flow rate of a processgas; and

FIG. 10 is a graph showing a relationship between internal pressures ingas retention portions of Comparative Example 1 and Embodiment 1, and aflow rate of a process gas.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be described indetails with reference to the attached drawings. Like reference numeralsdenotes like elements throughout and redundant descriptions will beomitted.

As shown in FIG. 1, a plasma processing apparatus 1 includes aprocessing container 2 having a cylindrical shape. An upper portion ofthe processing container 2 is opened, and a lower portion of theprocessing container 2 is closed. The processing container 2 is formedof, for example, aluminum, and is electrically grounded. An inner wallsurface of the processing container 2 is coated with a protective film,for example, alumina or the like.

A susceptor 3, which functions as a holding stage for holding asubstrate, for example, a semiconductor wafer (hereinafter, referred toas a wafer) W, is formed in the lower portion of the processingcontainer 2. The susceptor 3 is formed of, for example, aluminum, and aheater 5 that emits heat by applying power from an external power source4 is formed inside the susceptor 3. The wafer W on the susceptor 3 maybe heated to a predetermined temperature by the heater 5.

An exhaust pipe 11 through which the inside atmosphere of the processingcontainer 2 is exhausted by an exhauster 10, such as a vacuum pump orthe like, is coupled to the lower portion of the processing container 2.

A dielectric window 16 formed of a dielectric material, for example,quartz or the like, is disposed in the upper portion of the processingcontainer 2 through a sealing member 15, such as an O ring or the like,for obtaining air-tightness. As shown in FIG. 2, the dielectric window16 is approximately disc-shaped. Other dielectric materials, forexample, ceramics such as Al₂O₃, AlN, or the like, instead of quartz mayalso be used to form the dielectric window 16.

A planar slot plate, for example, a radial line slot plate 20 having adisc shape, is formed above the dielectric window 16. The radial lineslot plate 20 is formed of a thin copper disc plated or coated with aconductive material, for example, Ag, Au, or the like. In the radialline slot plate 20, a plurality of slots 21 are disposed in shape of aplurality of concentric circles.

A dielectric plate 25 for shortening a wavelength of microwaves isdisposed on an upper surface of the radial line slot plate 20. Thedielectric plate 25 is formed of a dielectric material, for example,Al₂O₃ or the like. Instead of Al₂O₃, other dielectric materials, forexample, ceramics such as quartz, AlN, or the like, may be used for thedielectric plate 25. The dielectric plate 25 is covered with a cover 26that is conductive, heat medium passages 27, each having an annularshape, are formed in the cover 26, and heat media flowing through theheat medium passages 27 allow the cover 26 and the dielectric window 16to maintain a predetermined temperature.

A coaxial waveguide 30 is connected to a center of the cover 26. Thecoaxial waveguide 30 includes an inner conductor 31 and an outerconductor 32. The inner conductor 31 penetrates a center of thedielectric plate 25 and is then connected to a center of the uppersurface of the radial line slot plate 20 described above. The pluralityof slots 21 formed in the radial line slot plate 20 are all arranged ona plurality of circumferences around the inner conductor 31.

A microwave supply device 35 is connected to the coaxial waveguide 30via a rectangular waveguide 36 and a mode converter 37. Microwaves of2.45 GHz, for example, generated in the microwave supply device 35 areemitted to the dielectric window 16 via the rectangular waveguide 36,the mode converter 37, the coaxial waveguide 30, the dielectric plate25, and the radial line slot plate 20. Also, an electric field is formedon the lower surface of the dielectric window 16 by the microwaves atthat time, and thus plasma is generated in the processing container 2.

A lower end 40 of the inner conductor 31 connected to the radial lineslot plate 20 is formed in a truncated cone shape. As such, since thelower end 40 of the inner conductor 31 is formed in a truncated coneshape, microwaves are efficiently propagated from the coaxial waveguide30 to the dielectric plate 25 and the radial line slot plate 20.

A process gas supplied from a gas supply source 50 is distributed by asplitter 51, and is introduced into the processing container 2 throughtwo supply passages 52 and 53. A plasma generation gas, such asnitrogen, Ar, oxygen, or the like, a source gas such as a CF-based gasor a CFH-based gas, and the like are used as the process gas.

Introducing units 55 and 56 for introducing the process gas are disposedon a ceiling surface and an inner side surface in the processingcontainer 2. The introducing unit 55 on the ceiling surface is disposedin a center of the ceiling surface of the processing container 2. Theintroducing unit 55 on the ceiling surface is connected to one supplypassage 52 penetrating the inner conductor 31 of the coaxial waveguide30.

A plurality of the introducing units 56 on the inner side surface of theprocessing container 2 are distributed in a circumferential direction ofthe inner side surface of the processing container 2 so as to surroundan area above the wafer W loaded on the susceptor 3. The introducingunit 56 on the inner side surface of the processing container 2 isconnected to the other supply passage 53 penetrating the side surface ofthe processing container 2. The process gas distributed by the splitter51 is introduced into the processing container 2 from the twointroducing units 55 and 56 through the supply passages 52 and 53.

As shown in FIG. 3, the introducing unit 55 on the ceiling surface isconstructed by leaving a gap from the lower surface of the innerconductor 31 of the coaxial waveguide 30 and disposing an injector block60 having a cylindrical shape in the gap. The injector block 60 isformed of a conductive material, for example, aluminum or the like, andis electrically grounded. A supporting block 59 is attached to the lowerend surface of the inner conductor 31 while leaving a suitable gap froman upper surface of the injector block 60. The radial line slot plate 20is supported between the supporting block 59 and the lower end surfaceof the inner conductor 31. An opening 52 a of the supply passage 52penetrating the centers of the inner conductor 31 and the supportingblock 59 is located in the center of the lower surface of the supportingblock 59. Cylinder-shaped gas retention portion 61 in which the opening52 a locates in the center is formed between the lower surface of thesupporting block 59 and the upper surface of the injector block 60.

A supporting portion 62 for supporting the injector block 60 is disposedin the center of the dielectric window 16. An upper portion of thesupporting portion 62 is a cylindrical shaped space having a sizecapable of receiving the injector block 60. A tapered surface 63 havinga cone shape with a diameter narrowing in downward direction is formedin a lower portion of the supporting portion 62.

A recess portion 65 that accommodates the process gas supplied from theopening 52 a at the lower surface center of the inner conductor 31 tothe gas retention portion 61 is formed in the center of the uppersurface of the injector block 60. The recess portion 65 is disposedfacing the opening 52 a of the supply passage 52.

As shown in FIGS. 4 and 5, a plurality of gas ejection holes 66 allowingcommunication between the gas retention portion 61 and the inside of theprocessing container 2 are formed in the injector block 60. No gasejection holes 66 are formed on a location facing the opening 52 a ofthe lower surface center of the inner conductor 31 (the lower surfacecenter of the supporting block 59), and the plurality of gas ejectionholes 66 are all disposed to surround the recess portion 65.

All of the gas ejection holes 66 have a flat cross-sectional shape thatis long in the circumferential direction having the recess portion 65 ina center and short in the radial direction having the recess portion 65in a center. Considering a mean free path of electrons and conductanceof the gas, the gas ejection hole 66 may have a width t of the radialdirection that is, for example, 1 mm or less (preferably from about 0.3to about 0.5 mm), and a length L of the circumference direction that is,for example, from about several mm to about ten and several mm. In theshown example, a plurality of gas ejection holes 66 are disposed alongthree concentric circumferences around the recess portion 65.

Since the lower portion of the supporting portion 62 supporting theinjector block 60 is the tapered surface 63 having a cone shape, the gasejection holes 66 are not directly seen by being covered by thedielectric window 16 when viewed upward from the inside of theprocessing container 2, as shown in FIG. 2.

As shown in FIG. 6, a protective film 67 against a gas is formed on thelower surface of the injector block 60. The protective film 67 is formedof, for example, yttria or the like. A periphery 66 a of the opening ofthe gas ejection hole 66 shown in the lower surface of the injectorblock 60 has a tapered shape. The protective film 67 is also formed onthe periphery 66 a of the opening of the gas ejection hole 66, which isformed in the taper-shaped portion.

An operation of the plasma processing apparatus 1 having theabove-described structure will now be described. Etching of a surface ofthe wafer W by using the process gas including the plasma generationgas, such as Ar, oxygen, or the like, and the source gas, such as theCF-based gas, the CFH-based gas, or the like, will be described as anexample of plasma processing.

As shown in FIG. 1, in the plasma processing apparatus 1, the wafer W istransferred to the processing container 2 and loaded on the susceptor 3.Exhaust through the exhaust pipe 11 is performed, and thus the inside ofthe processing container 2 is depressurized. The process gas includingthe plasma generation gas, such as Ar, oxygen, or the like and thesource gas, such as the CF-based gas, the CFH-based gas, or the like, isintroduced from the gas supply source 50 into the processing container2.

The process gases are introduced into the processing container 2 at thesame time from the introducing units 55 and 56 formed on the ceilingsurface and the inner side surface of the processing container 2. Aratio of the amounts of the process gases introduced from theintroducing units 55 and 56 is adjusted by the splitter 51 in such a waythat a uniform etching process is performed on the entire surface of thewafer W.

Also, according to an operation of the microwave supply device 35, anelectric field is generated in the lower surface of the dielectricwindow 16, and thus the process gas is plasmatized and an etchingprocess is performed on the surface of the wafer W by active speciesgenerated at that time. Also, after the etching process is performed fora predetermined period of time, the operation of the microwave supplydevice 35 and the supply of the process gas into the processingcontainer 2 are stopped, and the wafer W is transferred from theprocessing container 2. Thus, a series of the plasma etching processesare completed.

However, in the above-described plasma processing apparatus 1, since theprocess gas is plasmatized, a carbon-based product may be easily adheredto the gas ejection holes 66 of the injector block 60, especially in theintroducing unit 55 formed on the ceiling surface of the processingcontainer 2. Also, when the gas ejection holes 66 are blocked by theadhered product, the process gas is unable to be smoothly introduced tothe processing container 2. Moreover, uniformity of the etching withrespect to the surface of the wafer W is in disorder because a balancebetween the amounts of the process gases introduced from the introducingunit 56 on the inner side surface of the processing container 2 and theintroducing unit 55 on the ceiling surface of the processing container 2is changed.

Here, a main cause of generation of a carbon-based deposition in a gasejection hole was examined with respect to a conventional introducingunit for introducing a process gas. As shown in FIG. 7, a well knownstructure of a conventional introducing unit 100 for introducing aprocess gas is formed by providing a plurality of gas ejection holes 102on the entire area of an injector block 101 having a cylindrical shape.Each of the gas ejection holes 102 has a circular cross-sectional shapehaving a diameter of about 0.5 mm. An upper surface of the injectorblock 101 is a flat surface, and a portion corresponding to the recessportion 65 does not exist. Also, the plurality of gas ejection holes 102are provided uniformly on the entire lower surface of the injector block101 and are opened, and the gas ejection hole 102 is also formed in alocation facing the opening 52 a of the lower surface center of theinner conductor 31.

In such a conventional introducing unit 100 for introducing the processgas, since a cross-sectional area of each of the gas ejection holes 102is small, a resistance was large and an internal pressure of the gasretention portion 61 was high when the process gas supplied from thesupply passage 52 to the gas retention portion 61 passes through the gasejection holes 102. Also, it was guessed that, when the process gas isretained tentatively at a high concentration in the gas retentionportion 61, electrons or the like in the processing container 2 enterinto the gas retention portion 61 via the gas ejection holes 102, theprocess gas is plasmatized in the gas ejection holes 102, and thus thecarbon-based product is adhered to the gas ejection holes 66 a.

Also, in the conventional introducing unit 100 for introducing theprocess gas, the process gas intensively flew into the gas ejection hole102 in the location facing the opening 52 a of the lower surface centerof the inner conductor 31, and an inflow amount of the process gas waslow in the gas ejection holes 102 deviated from the opening 52 a oflower surface center of the inner conductor 31 (the lower surface centerof the supporting block 59). Thus, it was difficult to effectivelyreduce the internal pressure of the gas retention portion 61 even thoughthe number of gas ejection holes 102 was increased. Also, it isdifficult to evenly form the plurality of gas ejection holes 102 eachhaving a diameter of about 0.5 mm.

In the plasma processing apparatus 1 according to the presentembodiment, however, since the gas ejection holes 66 formed on theinjector block 60 of the introducing unit 55 have flat cross-sectionalshapes, the length L of the circumferential direction is sufficientlylong compared to the diameter (about 0.5 mm) of each of the conventionalgas ejection holes 102. Thus, according to the plasma processingapparatus 1 of the present embodiment, the cross-sectional areas of thegas ejection holes 66 are considerably large compared to those of arelated art, and the process gas easily gets out from the gas retentionportion 61 into the processing container 2. Accordingly, the internalpressure of the gas retention portion 61 is decreased, and thus aconcentration of the process gas in the gas retention portion 61 is alsodecreased. The gas ejection hole is not formed through the gas retentionportion 61, and thus it is difficult to plasmatize the process gas byelectrons or the like. As a result, for example, even when the electronsor the like in the processing container 2 enter the gas retentionportion 61 from the gas ejection holes 102, a possibility of the processgas to be plasmatized in the gas ejection holes 102 is decreased, andthus the carbon-based product is prevented from being adhered to the gasejection holes 66.

Also, in the plasma processing apparatus 1 according to the presentembodiment, no gas ejection holes 66 are formed at the location facingthe opening 52 a of the lower surface center of the inner conductor 31(the lower surface center of the supporting block 59), and the pluralityof gas ejection holes 66 are all disposed around the recess portion 65.Thus, the process gas supplied from the supply passage 52, whichpenetrates the center of the inner conductor 31, to the gas retentionportion 61 spreads from the center of the gas retention portion 61 tothe periphery of the gas retention portion 61, and then flows into eachof the gas ejection holes 66. Accordingly, the process gas flows intothe plurality of gas ejection holes 66 in almost the same state(pressure), thereby effectively reducing the internal pressure of thegas retention portion 61. In this case, since the recess portion 65 isformed in the center of the upper surface of the injector block 60, aforce (inertia) of the process gas that has flowed through the supplypassage 52 is remarkably reduced when the process gas flows into therecess portion 65. As a result, the process gas supplied form the supplypassage 52 to the gas retention portion 61 uniformly spreads on theentire region of the gas retention portion 61, and is thus introducedfrom all of the gas ejection holes 66 formed in the injector block 60into the processing container 2. Accordingly, the internal pressure ofthe gas retention portion 61 is more effectively decreased, and thus theconcentration of the process gas in the gas retention portion 61 isdecreased and the carbon-based product is more prevented from beingadhered to the gas ejection holes 66.

Also, in the plasma processing apparatus 1 according to the presentembodiment, all of the plurality of gas ejection holes 66 are notdirectly seen from the inside of the processing container 2 by beingcovered by the dielectric window 16, when viewed upward from the insideof the processing container 2. Accordingly, it is difficult for theelectrons or the like generated inside the processing container 2 toenter the gas ejection holes 66, and thus it is difficult for thecarbon-based deposition to be generated in the gas ejection holes 66.

Also, the injector block 60 is formed of a conductive material such asaluminum or the like, and is electrically grounded. Thus, even when theelectrons enter the gas ejection holes 66, the electrons contact theinner wall surfaces of the gas ejection holes 66, and thus are easilytrapped. At this time, since the width t of each of the gas ejectionholes 66 is narrow, for example, about 0.5 mm, a possibility of theelectrons to reach the gas retention portion 61 without contacting theinner wall surfaces of the gas ejection holes 66 is very low.

Also, the lower surface of the injector block 60 is protected by theprotective film 67 formed of yttria or the like on the lower surface ofthe injector block 60. In this case, since the protective film 67 isalso formed on the periphery 66 a of the tapered opening of each of thegas ejection holes 66, the opening of each of the gas ejection holes 66is protected from a gas. Also, since the opening of each of the gasejection holes 66 is formed in the tapered shape, the protective film 67may be easily formed on the periphery 66 a of the opening.

Accordingly, according to the plasma processing apparatus 1 of thepresent embodiment, the process gas is smoothly introduced to theprocessing container 2. Also, the etching is more uniformly performed onthe surface of the wafer W since the balance between the amounts of theprocess gases introduced from the introducing unit 55 on the ceilingsurface of the processing container 2 and the introducing unit 56 on theinner side surface of the processing container 2 is satisfactorilymaintained. Also, an operation of resolving blocking of the gas ejectionholes 66 is diminished, and thus maintenanceability is improved.

While this invention has been particularly shown and described withreference to exemplary embodiments thereof, the invention is not limitedto those examples. It will be understood by one of ordinary skill in theart that various changes in form and details may be made therein withoutdeparting from the spirit and scope of the invention as defined by theappended claims.

For example, an alumite process may be performed on the upper surface ofthe injector block 60 or inner surfaces of the gas ejection holes 66,thereby improving durability of the upper surface of the injector block60 or the inner surfaces of the gas ejection holes 66. In this case, aperiphery of an entrance portion of each of the gas ejection holes 66,which is shown on the upper surface of the injector block 60, may have atapered shape. Sizes of the plurality of gas ejection holes 66 formed inthe injector block 60 may be the same as or different from each other.Also, the plurality of gas ejection holes 66 may be arranged, forexample, in a spiral shape.

Although the embodiments of the present invention are applied to theplasma processing apparatus 1 for performing the etching process, thepresent invention may be applicable to plasma processing apparatusesthat perform a substrate process other than the etching process, forexample, a film-forming process. Also, a substrate that is processed bya plasma processing apparatus according to the present invention may bea semiconductor wafer, an organic EL substrate, a FPD (flat paneldisplay) substrate, or the like.

EMBODIMENTS

A relationship between a cross-sectional shape of a gas ejection holeformed in an injector block and an internal pressure of a gas retentionportion is examined.

COMPARATIVE EXAMPLE 1 (CONVENTIONAL EXAMPLE)

As shown in FIG. 8( a), in Comparative Example 1, 19 gas ejection holes102 each having a circular cross-sectional shape with a diameter of 0.5mm are formed in the injector block 101 having a disc shape with athickness of 8 mm. The gas ejection hole 102 is formed even on thecenter of the injector block 101, which is a location facing an openingof a supply passage of a process gas. The upper surface of the injectorblock 101 is flat and has no recess portion.

COMPARATIVE EXAMPLE 2

As shown in FIG. 8( b), in Comparative Example 2, 324 gas ejection holes102 each having a circular cross-sectional shape with a diameter of 0.5mm are formed in the injector block 101 having a disc shape with athickness of 8 mm. No gas ejection holes 102 are formed on the center ofthe injector block 101, which is a location facing an opening of asupply passage of a process gas. Also, the recess portion 65 is formedin the center of the upper surface of the injector block 101.

COMPARATIVE EXAMPLE 3

As shown in FIG. 8( c), in Comparative Example 3, 324 gas ejection holes102 each having a circular cross-sectional shape with a diameter of 0.5mm are formed in the injector block 101 having a disc shape with athickness of 4 mm. No gas ejection holes 102 are formed on the center ofthe injector block 101, which is a location facing an opening of asupply passage of a process gas. Also, the recess portion 65 is formedin the center of the upper surface of the injector block 101.

COMPARATIVE EXAMPLE 4

As shown in FIG. 8( d), in Comparative Example 4, 48 gas ejection holes102 each having a circular cross-sectional shape with a diameter of 0.5mm are formed in the injector block 101 having a disc shape with athickness of 8 mm. No gas ejection holes 102 are formed on the center ofthe injector block 101, which is a location facing an opening of asupply passage of a process gas. Also, the recess portion 65 is formedin the center of the upper surface of the injector block 101.

EMBODIMENT 1

As shown in FIG. 8( e), in Embodiment 1, 24 gas ejection holes 66 eachhaving a flat cross-sectional shape are formed in the injector block 60having a disc shape with a thickness of 8 mm. The width t of the gasejection hole 66 in the radial direction of the injector block 60 is 0.5mm, and the length L thereof in the circumferential direction of theinjector block 60 is from several mm to ten and several mm. No gasejection holes 66 are formed on the center of the injector block 60,which is a location facing an opening of a supply passage of a processgas. Also, the recess portion 65 is formed in the center of the uppersurface of the injector block 60.

EMBODIMENT 2

As shown in FIG. 8( f), in Embodiment 2, 12 gas ejection holes 66 eachhaving a flat cross-sectional shape are formed in the injector block 60having a disc shape with a thickness of 8 mm. The width t of the gasejection hole 66 in the radial direction of the injector block 60 is 0.5mm, and the length L thereof in the circumferential direction of theinjector block 60 is from several mm to ten and several mm. No gasejection holes 66 are formed on the center of the injector block 60,which is a location facing an opening of a supply passage of a processgas. Also, the recess portion 65 is formed in the center of the uppersurface of the injector block 60.

COMPARATIVE EXAMPLE 5

As shown in FIG. 8( g), in Comparative Example 5, only one gas ejectionhole 102 having a circular cross-sectional shape with a diameter of 2.5mm is formed on the center of the injector block 101 having a disc shapewith a thickness of 8 mm. The gas ejection hole 102 is formed on alocation facing an opening of a supply passage of a process gas. Theupper surface of the injector block 101 is flat and has no recessportion.

Differences between internal pressures of gas retention portion andinternal pressures of processing containers were measured with respectto the injector blocks of Comparative Examples 1 through 5 andEmbodiments 1 and 2. The measurement was performed while flowing an Argas at 100 mtorr and 100 sccm. Results of measuring the internalpressures of the gas retention portions and the internal pressures ofthe processing containers of Comparative Examples 1 through 5 andEmbodiments 1 and 2 are shown in Table 1.

TABLE 1 Comparative Comparative Comparative Comparative ComparativeEmbodiment Embodiment Example 1 Example 2 Example 3 Example 4 Example 51 2 Gas 650 Pa 550 Pa 350 Pa 1230 Pa 400 Pa 280 Pa 250 Pa retention 4.9T 4.1 T 2.6 T 9.5 T 3 T 2.1 T 1.87 T portion Processing  50 Pa  50 Pa 32 Pa  37 Pa  35 Pa  35 Pa  33 Pa Container 375 mT 375 mT 240 mT 277 mT260 mT 260 mT 247 mT

From the results of Table 1, the differences between the internalpressures of the gas retention portions and the internal pressures ofthe processing containers are small in the injector blocks ofEmbodiments 1 and 2 compared to the injector blocks of ComparativeExamples 1 through 5.

Next, flow rates for the injector blocks of Comparative Example 1 andEmbodiment 1 are changed to measure changes of the internal pressures ofthe gas retention portions. The flow rate of the Ar gas (100 mtorr) waschanged to 50 to 1000 sccm. The results are shown in FIGS. 9 and 10. Asshown in FIG. 9, in a splitter operating as a supplier, a pressure A ofComparative Example 1 and a pressure B of Embodiment 1 were increasedalmost proportionally. Here, as shown in FIG. 10, an internal pressure Dof the gas retention portion of Embodiment 1 was almost constantregardless of the increase of the flow rate. Meanwhile, an internalpressure C of the gas retention portion of Comparative Example 1 wasincreased in proportion to the increase of the flow rate.

According to the present invention, generation of a carbon-baseddeposition in an introducing unit for introducing a process gas to aprocessing container can be suppressed. Accordingly, in a plasmaprocessing apparatus that processes a substrate by plasmatizing theprocess gas introduced to the processing container, the process gas issmoothly introduced to the processing container. Also, uniformity ofetching on a surface of the substrate is improved since a balancebetween amounts of process gases introduced from an introducing unit ona side surface and an introducing unit on a ceiling surface issatisfactorily maintained. Also, an operation of resolving blocking of agas ejection hole is diminished, and thus maintenanceability isimproved.

The present invention is useful, for example, in semiconductormanufacturing fields.

What is claimed is:
 1. A plasma processing apparatus which processes asubstrate by plasmatizing a process gas introduced into a processingcontainer, wherein an introducing unit which introduces the process gasis formed on a ceiling surface of the processing container; a gasretention portion which gathers the process gas supplied from theoutside of the processing container through a supply passage, and aplurality of gas ejection holes which allow communication between thegas retention portion and the inside of the processing container areformed in the introducing unit; a gas ejection hole is not formed in alocation of the gas retention portion that faces an opening of thesupply passage; and a cross section of each of the gas ejection holeshas a flat shape.
 2. The plasma processing apparatus of claim 1, whereina recess portion accommodating the process gas supplied from the supplypassage to the gas retention portion is formed in the location of thegas retention portion that faces the opening of the supply passage. 3.The plasma processing apparatus of claim 1, wherein the opening of thesupply passage is located in the center of the gas retention portion,and the plurality of gas ejection holes are disposed in acircumferential direction having the opening of the supply passage in acenter.
 4. The plasma processing apparatus of claim 3, wherein each ofthe gas ejection holes has a flat cross-sectional shape that is long inthe circumferential direction having the opening of the supply passagein a center and short in a radial direction having the opening of thesupply passage in a center.
 5. The plasma processing apparatus of claim4, wherein each of the gas ejection holes has a width of 1 mm or less inthe radial direction having the opening of the supply passage and alength of several mm to ten and several mm in the circumferentialdirection having the opening of the supply passage in a center.
 6. Theplasma processing apparatus of claims 1, wherein the gas ejection holesare formed in an injector block formed of a conductive material, and theinjector block is electrically grounded.
 7. The plasma processingapparatus of claim 6, wherein a protective film which increasesdetachability is formed on a surface of the injector block that facesthe inside of the processing container.
 8. The plasma processingapparatus of claim 7, wherein a periphery of the opening of the gasejection hole that faces the inside of the processing container has atapered shape.
 9. The plasma processing apparatus of claims 1, wherein adielectric window is formed on the ceiling surface of the processingcontainer so that the gas ejection holes are not directly seen by beingcovered by the dielectric window when viewed upward from the inside ofthe processing container.